A lithium ion battery cathode active material is typically expressed bya compositional formula: LixNi1−yMyO2+α  (1)
(in the formula, M is one or more selected from Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Al, Bi, Sn, Mg, Ca, B, and Zr, 0.9≤x≤1.2, 0<y≤0.7, and α>0.1).
In addition to the above formula, there isa compositional formula: Li(LixNi1−x−yMy)O2+α  (2)
(in the formula, M is one or more selected from Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Al, Bi, Sn, Mg, Ca, B, and Zr, 0≤x≤0.1, 0<y≤0.7, and α>0).
For example, a nickel salt, a cobalt salt, and a manganese salt are reacted as a material with a sodium hydroxide or an ammonium carbonate, and a nickel hydroxide or a manganese carbonate is obtained. The nickel hydroxide or the manganese carbonate is mixed and calcined with lithium (a lithium hydroxide), and a lithium/nickel/manganese-based cathode active material is obtained.
In this sort of case, a method is employed in which a nickel salt solution and a manganese salt solution are injected into a stirred reactor, and a Ni—Mn composite hydroxide or carbonate is precipitated.